1. Field of the Invention
The present invention relates generally to ditch liners and more specifically to modular ditch liners, which allow a ditch liner to be assembled from a plurality of ditch liner sections.
2. Discussion of the Prior Art
There are two different types of ditch liners. The first type of ditch liner is an open ditch liner. An example of an open type of ditch liner is found in U.S. Pat. No. 3,854,292 to Nienstadt. Nienstadt uses a relatively light plastic resin that is retained with a quantity of stakes. The second type of ditch liner is a closed ditch liner. The closed ditch liner includes a substantially U-shaped trough with a cover. The cover may have openings formed therethrough. Three examples of closed type ditch liners are found in U.S. Pat. No. 5,226,748 to Barenwald et al., U.S. Pat. No. 5,443,327 to Akkala et al., and U.S. Pat. No. 5,522,675 to Gunter. The Barenwald et al. and Gunter patents disclose using relatively complicated connecting devices to retain each liner section in tight connection to each other.
Accordingly, there is a clearly felt need in the art for a modular ditch liner which is fabricated from a heavy, yet economical material; does not require a relatively complicated connecting device; and does not require a perfect trench for installation.
The present invention provides a modular ditch liner that does not require complicated installation and assembly. An open modular ditch liner includes a plurality of open liner sections and at least one alignment key. The cross section of each open liner section includes a substantially concave shape formed on a top thereof. The plurality of open liner sections are preferably fabricated from cement block on a cement block casting machine. Casting cement blocks is a cost effective manufacturing process relative to cast iron or open cast molding. A key slot is formed on at least one side of each open liner section to receive a single alignment key. However, the at least one key slot may be replaced with at least one key opening. Each key opening is formed through a length of the open liner section, near a side thereof. The key opening is sized to receive an alignment key.
A closed modular ditch liner includes a plurality of closed liner sections, a plurality of covers, and at least one alignment key. The cross section of each closed liner section includes at least one trough contour and a single cover retention lip formed on a top end of each side thereof. The plurality of closed liner sections and covers are preferably fabricated from cement block on a cement block casting machine. Each cover is laterally retained between the two cover retention lips. A key slot is formed on at least one side of the closed liner section to receive a single alignment key. However, the at least one key slot may be replaced with at least one key opening. Each key opening is formed through a length of the closed liner section, near a side thereof. The key opening is sized to receive an alignment key.
The key slot may also include a positive taper or an interference fit. The key slot with an interference fit may have the shape of a negative taper or a substantially rounded shape. The key slot with an interference slot would provide an interference fit to an alignment key. The alignment key includes a block embodiment or an extruded embodiment. The block alignment key would be preferably used in the positive taper key slot. The length of a block alignment key would preferably be as long as an open liner section. Each block alignment key would engage two adjacent open liner sections. The extruded alignment key would be fabricated from an extruded material and preferably retained in an interference fit key slot.
An alignment key may be replaced by a riser section. The riser section includes a side member and an alignment key projection. The length of the riser section is preferably the same as that of the open liner section. The side member constrains the flow of fluid relative to the open liner section. The alignment key projection is sized to be received by one of the key slots of the open liner section. Further, the open liner sections may be formed as a trapezoid to allow the open liner sections to fit curved drain ditch applications. At least one end of the open liner section is angled.
Accordingly, it is an object of the present invention to provide a modular ditch liner that is fabricated from a heavy, yet economical material.
It is a further object of the present invention to provide a modular ditch liner that utilizes an uncomplicated connection device.
Finally, it is another object of the present invention to provide a modular ditch liner that does not require the creation of a perfect trench for installation.
These and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification.